Within the human body, different cells may interact with one another. For example, normal blood formation involves interactions between hematopoietic stem cells (HSCs) and extrinsic signals mediated via niches located in the endosteal and vascular regions of the bone marrow. Studying cellular interactions may provide insight with regard to roles that certain cell-to-cell interactions play in the progression, control, etc. of certain diseases. Some cell-to-cell studies involve the immobilization of a first layer of cells, and then the examination of cell changes that occur as a result of a label (e.g., a drug or a toxin) being added to the layer of cells.